第二章：数据结构-enum:枚举类型-比较Enum

2.1.3 比较Enum
由于枚举成员是无序的，所以它们只支持按同一性和相等性进行比较。

import enum

class BugStatus(enum.Enum):

    new = 7
    incomplete = 6
    invalid = 5
    wont_fix = 4
    in_progress = 3
    fix_committed = 2
    fix_relessed = 1

actual_state = BugStatus.wont_fix
desired_state = BugStatus.fix_relessed

print('Equality:',
      actual_state == desired_state,
      actual_state == BugStatus.wont_fix)
print('Identity:',
      actual_state is desired_state,
      actual_state is BugStatus.wont_fix)
print('Ordered by value:')

try:
    print('\n'.join(' ' + s.name for s in sorted(BugStatus)))
except TypeError as err:
    print(' Cannot sort:{}'.format(err))

大于和小于比较符会产生TypeError异常。
运行结果：

Equality: False True
Identity: False True
Ordered by value:
Cannot sort:’<’ not supported between instances of ‘BugStatus’ and ‘BugStatus’

有些枚举中的成员要表现得更像数字，例如，要支持比较，对于这些枚举要使用IntEnum类。

import enum

class BugStatus(enum.IntEnum):

    new = 7
    incomplete = 6
    invalid = 5
    wont_fix = 4
    in_progress = 3
    fix_committed = 2
    fix_relesed = 1

print('Ordered by value:')
print('\n'.join(' ' + s.name for s in sorted(BugStatus)))

运行结果：

Ordered by value:
fix_relesed
fix_committed
in_progress
wont_fix
invalid
incomplete
new